U.S. patent application number 11/928334 was filed with the patent office on 2008-11-27 for random access communication method and mobile communication system in mobile communication system.
Invention is credited to Suguru Nakada.
Application Number | 20080291880 11/928334 |
Document ID | / |
Family ID | 38982734 |
Filed Date | 2008-11-27 |
United States Patent
Application |
20080291880 |
Kind Code |
A1 |
Nakada; Suguru |
November 27, 2008 |
RANDOM ACCESS COMMUNICATION METHOD AND MOBILE COMMUNICATION SYSTEM
IN MOBILE COMMUNICATION SYSTEM
Abstract
The random access communication method according to the present
invention includes a mobile station transmitting a transmission
continuation request signal which requests a continuation of
transmission of random access data to a base station during
transmission of the random access data, the base station judging,
upon receiving a transmission continuation request signal from the
mobile station, whether or not to permit a continuation of
transmission of the random access data depending on the current
communication situation, the base station transmitting a
transmission continuation permission signal or a transmission
continuation rejection signal to the mobile station depending on
whether or not to permit the continuation of transmission of the
random access data, and the mobile station continuing, upon
receiving the transmission continuation permission signal from the
base station, transmission of the random access data.
Inventors: |
Nakada; Suguru; (Tokyo,
JP) |
Correspondence
Address: |
NEC CORPORATION OF AMERICA
6535 N. STATE HWY 161
IRVING
TX
75039
US
|
Family ID: |
38982734 |
Appl. No.: |
11/928334 |
Filed: |
October 30, 2007 |
Current U.S.
Class: |
370/338 |
Current CPC
Class: |
H04W 74/0866 20130101;
H04W 74/002 20130101; H04W 74/0833 20130101 |
Class at
Publication: |
370/338 |
International
Class: |
H04Q 7/00 20060101
H04Q007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 13, 2006 |
JP |
2006-306552 |
Claims
1. A random access communication method in a mobile communication
system made up of a base station and a plurality of mobile stations
which carry out random access communication with the base station,
comprising: the mobile station transmitting a transmission
continuation request signal which requests a continuation of
transmission of the random access data to the base station during
transmission of the random access data, the base station judging,
when the transmission continuation request signal is received from
the mobile station, whether or not to permit the continuation of
transmission of the random access data depending on the current
communication situation; the base station transmitting a
transmission continuation permission signal or a transmission
continuation rejection signal to the mobile station depending on
whether or not to permit the continuation of transmission of the
random access data; and the mobile station continuing, when the
transmission continuation permission signal is received from the
base station, transmission of the random access data.
2. The random access communication method according to claim 1,
wherein the transmission continuation request signal is transmitted
using a radio channel other than the radio channel used for
transmission of the random access data.
3. The random access communication method according to claim 1,
wherein the transmission continuation request signal is transmitted
embedded at some midpoint of the random access data using the radio
channel used to transmit the random access data.
4. The random access communication method according to claim 1,
wherein the current communication situation is judged based on a
reception situation of a transmission start request signal which
requests that the transmission of random access data be started
from a mobile station other than the mobile station which
transmitted the transmission continuation request signal.
5. The random access communication method according to claim 1,
wherein the current communication situation is judged based on the
reception quality of the random access data received from the
mobile station which has transmitted the transmission continuation
request signal.
6. The random access communication method according to claim 1,
wherein the current communication situation is judged based on the
amount of random access data received from the mobile station which
has transmitted the transmission continuation request signal.
7. A mobile communication system comprising: a base station; and a
plurality of mobile stations which carry out a random access
communication with the base station; wherein the mobile station
comprising: a mobile station communication section for carrying out
a radio communication with the base station: and mobile station
random access controller for controlling the mobile station
communication section during transmission of the random access
data, for transmitting a transmission continuation request signal
which requests a continuation of transmission of the random access
data to the base station, for controlling, when the mobile station
communication section receives a transmission continuation
permission signal which permits the continuation of transmission of
the random access data from the base station, the mobile station
communication section to continue transmission of the random access
data, and the base station comprising: a base station communication
section which carries out a radio communication with the mobile
station; and a base station random access controller which judges,
when the base station communication section receives the
transmission continuation request signal from the mobile station,
whether or not to permit a continuation of transmission of the
random access data based on the current communication situation,
controls the base station communication section depending on
whether or not to permit the transmission continuation, and
transmits a transmission continuation permission signal or a
transmission continuation rejection signal to the mobile
station.
8. The mobile communication system according to claim 7, wherein
the mobile station random access controller controls the mobile
station communication section and transmits the transmission
continuation request signal using a radio channel other than the
radio channel used for transmission of the random access data.
9. The mobile communication system according to claim 7, wherein
the mobile station random access controller controls the mobile
station communication section and transmits the transmission
continuation request signal embedded at some midpoint of the random
access data using the radio channel used for transmission of the
random access data.
10. The mobile communication system according to claim 7, wherein
the base station random access controller judges the current
communication situation based on a reception situation of the
transmission start request signal which requests that the
transmission of random access data be started from a mobile station
other than the mobile station which transmitted the transmission
continuation request signal.
11. The mobile communication system according to claim 7, wherein
the base station random access controller judges the current
communication situation based on the reception quality of the
random access data received from the mobile station which has
transmitted the transmission continuation request signal.
12. The mobile communication system according to claim 7, wherein
the base station random access controller judges the current
communication situation based on the amount of random access data
received from the mobile station which has transmitted the
transmission continuation request signal.
13. A mobile communication system comprising: a base station, and a
plurality of mobile stations which carry out a random access
communication with the base station; wherein the mobile station
comprising: mobile station communication means for carrying out a
radio communication with the base station; and mobile station
random access control means for controlling the mobile station
communication means during transmission of the random access data,
for transmitting a transmission continuation request signal which
requests a continuation of transmission of the random access data
to the base station, for controlling, when the mobile station
communication means receives a transmission continuation permission
signal which permits the continuation of transmission of the random
access data from the base station, the mobile station communication
means to continue transmission of the random access data, and the
base station comprising: base station communication means for
carrying out a radio communication with the mobile station; and
base station random access control means for judging, when the base
station communication means receives the transmission continuation
request signal from the mobile station, whether or not to permit a
continuation of transmission of the random access data based on the
current communication situation, controlling the base station
communication means depending on whether or not to permit the
transmission continuation, and transmitting a transmission
continuation permission signal or a transmission continuation
rejection signal to the mobile station.
Description
[0001] This application is based upon and claims the benefit of
priority from Japanese patent application No. 2006-306552, filed on
Nov. 13, 2006, the disclosure of which is incorporated herein in
its entirety by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates to a technology for improving
utilizaton efficiency of a radio channel for random access
communication in a mobile communication system.
[0004] 2. Description of the Related Art
[0005] Nowadays, a major shift in the way that information is
transmitting through a mobile communication system such as a
cellular phone system is the shift from speech to packet data. This
is because cellular phones are provided with higher functionality,
and functions such as site browsing, e-mail, camera, music/video
reproduction have been successively added so that large-volume data
associated with these functions is transmitted through
networks.
[0006] In order to transmit such packet data from a mobile station
such as a cellular phone to a base station, many mobile
communication systems use a random access communication scheme. The
random access communication scheme is suitable for a communication
which does not have information to be continuously transmitted such
as speech calls.
[0007] The random access communication scheme shares one radio
channel determined by frequency, time slot, spreading code or the
like among a plurality of mobile stations (e.g., see
JP-A-1996-181645, JP-A-1997-200848, JP-A-1998-173584 and
JP-A-2005-101990).
[0008] Therefore, to prevent a specific mobile station from
occupying a radio channel for a long time, when the size of random
access data is large, the mobile station divides the data into
portions of a predetermined data length and transmits the divided
random access data to the base station after an interval.
[0009] For example, a mobile communication system based on a W-CDMA
(Wideband Code Division Multiple Access) scheme is provided with a
radio channel called PRACH (Physical Random Access Channel) as a
radio channel for random access communication.
[0010] Here, the random access communication method in a related
mobile communication system will be explained with reference to
FIG. 1 and FIG. 2.
[0011] Referring to FIG. 1 and FIG. 2, when random access data to
be transmitted to a base station is produced in step 801, a mobile
station sends a transmission start request signal prearranged with
the base station to the base station before transmitting random
access data in step 802.
[0012] When the transmission start request signal is received from
the mobile station in step 803, the base station judges whether or
not to permit transmission of the random access data in step 804
and transmits a transmission start permission signal or a
transmission start rejection signal to the mobile station according
to the judgment result in steps 805 and 806.
[0013] When a transmission start rejection signal is received from
the base station (in the case of situation [A] in FIG. 1) in step
807 or when a transmission start permission signal cannot be
received from the base station after a lapse of a predetermined
time in step 809, the mobile station repeatedly transmits a
transmission start request signal to the base station until it can
receive a transmission start permission signal.
[0014] On the other hand, when a transmission start permission
signal is received from the base station in step 808 (in the case
of situation [B] in FIG. 1), the mobile station starts transmission
of random access data of a predetermined data length to the base
station in step 810. The base station performs reception processing
on the random access data in step 811.
[0015] When the transmission of the random access data of the
predetermined data length is completed in step 812, the mobile
station stops the transmission temporarily in step 813. In that
case, when there still remains some random access data in the
mobile station in step 814, the mobile station repeatedly transmits
a transmission start request signal to the base station until it
can receive a transmission start permission signal again from the
base station.
[0016] Hereinafter, the above described processing is repeated and
transmission of the random access data from the mobile station is
completed when there remains no more random access data in step
815.
[0017] In the above described random access communication method,
the mobile station and the base station must communicate about
permission or rejection for a transmission start every time the
mobile station transmits random access data of a predetermined data
length to the base station. However, there can also be cases where
no mobile station is transmitting random access data while these
exchanges are being carried out.
[0018] However, in order to efficiently transmit the increasing
amount of packet data daily, it is necessary to efficiently use a
radio channel for random access communication and to reduce the
time during which no mobile station is transmitting data as much as
possible. Furthermore, mobile stations also require that random
access data be transmitted as early as possible.
SUMMARY OF THE INVENTION
[0019] Therefore, it is an object of the present invention to
provide a random access communication method in a mobile
communication system and to provide a mobile communication system
capable of improving utilization the efficiency of a radio channel
for random access communication.
[0020] In order to attain the above described object, the random
access communication method of the present invention is a random
access communication method in a mobile communication system made
up of a base station and a plurality of mobile stations which carry
out a random access communication with the base station, including
a mobile station transmitting a transmission continuation request
signal which requests a continuation of transmission of the random
access data to the base station during transmission of the random
access data, the base station judging, when the transmission
continuation request signal is received from the mobile station,
whether or not to permit the continuation of transmission of the
random access data depending on the current communication
situation, the base station transmitting a transmission
continuation permission signal or a transmission continuation
rejection signal to the mobile station depending on whether or not
to permit the continuation of transmission of the random access
data, and the mobile station continuing, when the transmission
continuation permission signal is received from the base station,
the transmission of the random access data.
[0021] In order to attain the above described object, the mobile
communication system of the present invention is a mobile
communication system comprising a base station and a plurality of
mobile stations which carry out a random access communication with
the base station, wherein the mobile station including a mobile
station communication section for carrying out a radio
communication with the base station, and mobile station random
access controller for controlling the mobile station communication
section during transmission of the random access data, for
transmitting a transmission continuation request signal which
requests a continuation of transmission of the random access data
to the base station for controlling, when the mobile station
communication section receives a transmission continuation
permission signal which permits the continuation of transmission of
the random access data from the base station, the mobile station
communication section to continue transmission of the random access
data, and the base station including a base station communication
section which carries out a radio communication with the mobile
station and a base station random access controller which judges,
is when the base station communication section receives the
transmission continuation request signal from the mobile station,
whether or not to permit a continuation of transmission of the
random access data based on the current communication situation,
controls the base station communication section depending on
whether or not to permit the transmission continuation, and
transmits a transmission continuation permission signal or a
transmission continuation rejection signal to the mobile
station.
[0022] The above and other objects, features, and advantages of the
present invention will become apparent from the following
description with reference to the accompanying drawings which
illustrate examples of the present invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 illustrates an overview of a random access
communication method in a related mobile communication system;
[0024] FIG. 2 is a flow chart illustrating the flow of the random
access communication method in the related mobile communication
system;
[0025] FIG. 3 shows the configuration of a mobile communication
system of the present invention;
[0026] FIG. 4 illustrates an overview of the random access
communication method in the mobile communication system shown in
FIG. 3;
[0027] FIG. 5 illustrates an overview of the random access
communication to method in the mobile communication system shown in
FIG. 3;
[0028] FIG. 6 is a flow chart illustrating the flow of the random
access communication method in the mobile communication system
shown in FIG. 3;
[0029] FIG. 7 is a block diagram showing the configuration of the
base station shown in FIG. 3; and
[0030] FIG. 8 is a block diagram showing the configuration of the
mobile station shown in FIG. 3.
DESCRIPTION OF THE PREFERRED EXEMPLARY EMBODIMENTS
[0031] FIG. 3 shows the configuration of a mobile communication
system according to an exemplary embodiment of the present
invention.
[0032] Referring to FIG. 3, the mobile communication system of this
exemplary embodiment includes base station 10 and a plurality of
mobile stations 20.
[0033] FIG. 3 shows an example when the present invention is
applied to a general cellular phone system based on a CDMA scheme
but the present invention is not limited to the cellular phone
system.
[0034] Furthermore, the present invention presupposes that mobile
station 20 has already received a control signal including
information on base station 10 from base station 10 before starting
a random access communication.
[0035] Hereinafter, the random access communication method in the
mobile communication system of this exemplary embodiment shown in
FIG. 3 will be explained with reference to FIG. 4 to FIG. 6.
[0036] Referring to FIG. 4 to FIG. 6, when random access data to be
transmitted to base station 10 is produced in step 401, mobile
station 20 transmits a transmission start request signal
prearranged with base station 10 to base station 10 before
transmitting the random access data in step 402.
[0037] Upon receiving the transmission start request signal from
mobile station 20 in step 403, base station 10 judges whether or
not to permit transmission of the random access data in step 404
and transmits a transmission start pemission signal or transmission
start rejection signal to mobile station 20 depending on the
judgment result in steps 405 and 406.
[0038] When the transmission start rejection signal is received
from base station 10 in step 407 or when it is not possible to
receive any transmission start permission signal from base station
10 after a lapse of a predetermined time in step 409, mobile
station 20 repeatedly transmits a transmission start request signal
to base station 10 until it can receive a transmission start
permission signal from base station 10.
[0039] On the other hand, when a transmission start permission
signal is received from base station 10 in step 408, mobile station
20 starts transmission of random access data of a predetermined
data length to base station 10 in stop 410. Base station 10
performs reception processing on the random access data in step
411.
[0040] The above described processing is common to the random
access communication method shown in FIG. 1 and FIG. 2.
[0041] Next, in step 412, mobile station 20 judges, even after
transmission of random access data of the predetermined data
length, currently being transmitted, is completed, whether or not
there still remains random access data of a predetermined data
length or longer in mobile station 20. When there still remains
data of the predetermined data length or longer, mobile station 20
transmits a transmission continuation request signal prearranged
with base station 10 during transmission of the random access data
to base station 10 in step 413.
[0042] As for the method of transmitting a transmission
continuation request signal, a method of embedding the transmission
continuation request signal at some midpoint of the random access
data using a radio channel used to transmit the random access data
(FIG. 4 and FIG. 5) or a method using a different radio channel
(radio channel determined by a spreading code or frequency used)
may be used.
[0043] When the transmission continuation request signal is
received from mobile station 20 in step 414, base station 10 judges
whether or not to permit a continuation of transmission of the
random access data depending on the current communication situation
in step 415 and transmits a transmission continuation permission
signal or transmission continuation rejection signal to mobile
station 20 depending on the judgment result in steps 416 and
417.
[0044] In the judgment in step 415, the current communication
situation can be judged using the following information (1) to (3),
for example. However, all the following information need not always
be used and any one of them may be used.
[0045] (1) Reception situation of a transmission start request
signal from another mobile station 20
[0046] (2) Reception quality of random access data received from
mobile station 20
[0047] (3) Amount of random access data received so far from mobile
station 20
[0048] The case using (1) assumes a judgment that transmission
continuation will not be permitted when a transmission start
request signal is received from another mobile station 20 a
predetermined number of times or more per unit time and
transmission continuation will be permitted otherwise.
[0049] The case using (2) assumes a judgment that reception quality
is judged to be bad and transmission continuation will not be
permitted when the error rate of random access data received from
mobile station 20 reaches or exceeds a predetermined value and
transmission continuation will be permitted otherwise.
[0050] The case using (3) assumes a judgment that the radio channel
is excessively occupied and transmission continuation will not be
permitted when the amount of random access data received from
mobile station 20 reaches or exceeds a predetermined data length
and transmission continuation will be permitted otherwise.
[0051] Upon receiving a transmission continuation permission signal
from base station 10 in step 418, mobile station 20 continues to
transmit random access data of a predetermined data length to base
station 10 even after the transmission of the random access data of
a predetermined data length currently being transmitted is
completed in step 419. If there still remains random access data of
a predetermined data length or longer in mobile station 20 even
after the transmission of the random access data of the
predetermined data length is completed, mobile station 20 transmits
a transmission continuation request signal to base station 10 once
again.
[0052] On the other hand, when a transmission continuation
rejection signal is received from base station 10 in step 420 (in
the case of situation [a] in FIG. 4) or when a transmission
continuation permission signal cannot be received from base station
10 after a lapse of a predetermined time in step 421 (in the case
of situation [b] in FIG. 5), mobile station 20 stops transmission
of the random access data after transmission of the random access
data of the predetermined data length currently being transmitted
is completed in step 422.
[0053] When the random access data that still remains in mobile
station 20 after the transmission of the random access data of the
predetermined data length currently being transmitted is completed
is less than the predetermined length, mobile station 20 does not
transmit any transmission continuation request signal to base
station 10, transmits all the remaining random access data in step
423 and completes transmission of the random access data (in the
case of situation [c] in FIG. 5).
[0054] Hereinafter, the configurations of base station 10 and
mobile station 20 which realize the above described operations will
be explained.
[0055] FIG. 7 is a block diagram showing the configuration of base
station 10 shown in FIG. 3.
[0056] Referring to FIG. 7, base station 10 has antenna section 11,
radio modulator 12, baseband signal processor 13 and common
controller 14. Furthermore, baseband signal processor 13 has timing
correlator 15, RAKE receiver 16, symbol rate signal processor 17,
spreader 18 and base station random access controller 19.
[0057] That is, base station 10 has the configuration in which base
station random access controller 19 is added to the basic
configuration of a general base station based on a COMA scheme.
[0058] Antenna section 11, radio modulator 12, timing correlator
15, RAKE receiver 16, symbol rate signal processor 17 and spreader
18 constitute a base station communication section which carries
out radio communication with mobile station 20.
[0059] Base station random access controller 19 receives a
transmission start request signal and a transmission continuation
request signal transmitted from mobile station 20 and performs
transmission control of a transmission start permission
signal/transmission start rejection signal, transmission
continuation permission signal/transmission continuation rejection
signal based on various kinds of information.
[0060] In base station 10 configured as shown above, various types
of signals (transmission start permission signal, transmission
start on signal or the like) transmitted from mobile station 20 are
received by antenna section 11, demodulated into a baseband signal
by radio modulator 12 and then subjected to detection processing by
timing correlator 15. When a signal is detected, information of the
detection is notified to base station random access controller 19
via RAKE receiver 16 and symbol rate signal processor 17. Base
station random access controller 19 instructs symbol rate signal
processor 17 to transmit signals that are selected for transmission
to mobile station 20 (transmission start permission signal,
transmission start rejection signal, transmission continuation
permission signal and transmission continuation rejection signal).
These signals are converted to code strings which make up the
signals in question at symbol rate signal processor 17, are
subjected to spreading processing at spreader 18, are subjected to
modulation processing at radio modulator 12 and then are
transmitted from antenna section 11 to mobile station 20.
[0061] Furthermore, random access data transmitted from mobile
station 20 is received at antenna section 11 and demodulated into a
baseband signal at radio modulator 12, and then subjected to
detection processing at timing correlator 15. Path timing
information of the random access data is set in RAKE receiver 16.
After that, the random access data is subjected to despreading
processing and path diversity reception processing at RAKE receiver
16, is subjected to error correcting processing and de-interleaving
processing or the like at symbol rate signal processor 17 and then
is sent to a higher apparatus via common controller 14.
[0062] FIG. 8 is a block diagram showing the configuration of
mobile station 20 shown in FIG. 3
[0063] Referring to FIG. 8, mobile station 20 has antenna section
21, radio modulator 22, baseband signal processor 23 and common
controller 24. Furthermore, baseband signal processor 23 has timing
correlator 25, RAKE receiver 26, symbol rate signal processor 27,
spreader 28 and mobile station random access controller 29.
[0064] That is, mobile station 20 a configuration in which mobile
station random access controller 29 is added to the basic
configuration of a general mobile station based on a COMA
scheme.
[0065] Antenna section 21, radio modulator 22, timing correlator
25, RAKE receiver 26, symbol rate signal processor 27 and spreader
28 constitute a mobile station communication section which carries
out radio communication with base station 10.
[0066] Mobile station random access controller 29 receives a
transmission start permission signal/transmission start rejection
signal and transmission continuation permission signal/transmission
continuation rejection signal transmitted from base station 10 and
performs transmission controls on the transmission start request
signal, transmission continuation request signal and random access
data based on various kinds of information.
[0067] As for mobile station 20 configured as shown above, various
signals transmitted from base station 10 (transmission start
permission signal, transmission start rejection signal,
transmission continuation permission signal, transmission
continuation rejection signal or the like) are received at antenna
section 21 demodulated into a baseband signal at radio modulator
22, and then subjected to detection processing at timing correlator
25. When a signal is detected, the information of the detection is
notified to mobile station random access controller 29 via RAKE
receiver 26 and symbol rate signal processor 27. Mobile station
random access controller 29 instructs symbol rate signal processor
27 to transmit the signals that are selected for transmission to
base station 10 (transmission start request signal, transmission
continuation request signal or the like) and to transmit the random
access data received via common controller 24 from a higher layer
processor. These signals or the like are converted to code strings
that make up the signals in question at symbol rate signal
processor 27, are subjected to spreading processing at spreader 28,
are subjected to modulation processing at radio modulator 22 and
then are transmitted from antenna section 21 to base station
10.
[0068] As described above, according to the random access
communication method shown in FIG. 1 and FIG. 2, the mobile station
must exchange signals that permit/reject a transmission start with
the base stations every time it transmits random access data of a
predetermined data length to the base station, and therefore
wasteful delays are produced during transmission of the random
access data.
[0069] On the other hand, according to this exemplary embodiment,
mobile station 20 transmits a transmission continuation request
signal to base station 10 during transmission of the random access
data, base station 10 judges whether or not to permit transmission
continuation depending on the current communication situation,
transmits a transmission continuation permission signal to mobile
station 20 when transmission continuation is permitted, and when
the transmission continuation permission signal is received from
base station 10, mobile station 20 continues transmission of the
random access data.
[0070] Therefore, it is possible to make variable the data length
of random access data transmitted from mobile station 20 to base
station 10 depending on the current communication situation, and
thereby also to continuously transmit random access data, for
example, from mobile station 20 to base station 10.
[0071] Therefore, it is possible to efficiently use a radio channel
for random access and thereby minimize wasteful delays produced in
the mobile communication system shown in FIG. 1 and FIG. 2.
[0072] The present invention is not limited to the above described
cellular phone system and is also applicable to mobile
communication systems based on other schemes. Furthermore, since a
feature of the present invention lies in control over "transmission
continuation" of random access data, the present invention is also
applicable to such a communication scheme in which random access
data is transmitted abruptly without control over "transmission
start" at a preceding stage thereof.
[0073] While the invention has been particularly shown and
described with reference to exemplary embodiments thereof the
invention is not limited to these exemplary embodiments. It will be
understood by those of ordinary skill in the art that various
changes in form and details may be made therein without departing
from the spirit and scope of the present invention as defined by
the claims.
* * * * *